speed {adehabitat} | R Documentation |
speed
measures the speed between successive relocations of
animals, using objects of class traj
.
speed(x, id = levels(x$id), burst = levels(x$burst), date = NULL, units = c("seconds", "hours", "days"))
x |
an object of class traj |
id |
a character vector giving the identity of the animals for which the speed is to be computed |
burst |
a character vector giving the identity of the circuits
for which the speed is to be computed (see traj ) |
date |
a vector of class POSIXct of length 2 (beginning, end)
delimiting the period of interest |
units |
a character string. It determines how the
speeds are computed. For example, if the coordinates are given in
meters, and if units = "seconds" , speeds are returned in
meters per second. |
Returns a data frame with the following components:
id |
the identity of the animal |
x |
if the speed is computed between the relocation 1 and 2, the x coordinate of the relocation 1. |
y |
if the speed is computed between the relocation 1 and 2, the y coordinate of the relocation 1. |
date |
a vector of class POSIXct , giving the date of
relocation 1. |
burst |
the identity of the circuit |
sp.x |
the computed speed of the animal in the x direction |
sp.y |
the computed speed of the animal in the y direction |
speed |
the computed speed of the animal on the plane. |
dt |
the duration between the two relocations (in the units given
by the parameter units ). |
The function speed
is deprecated. The class ltraj
computes the speeds automatically (see ltraj
).
Clement Calenge clement.calenge@oncfs.gouv.fr
## Not run: #### Computes the speed for each wild boar #### monitored at Puechabon data(puechcirc) puechcirc <- ltraj2traj(puechcirc) puechcirc plot(puechcirc) sp <- speed(puechcirc) sp[1:4,] ## End(Not run)